Optical readers having 2D image sensors commonly are used to read both 1D and 2D symbols. Some optical readers having a 2D image sensor read a 1 D symbol by capturing a 2D image representation, or “frame” of image data corresponding to a target area which comprises a 1 D symbol, and launching a scan line or lines in order to attempt to decode for 1 D symbols which may be represented in the area. Other optical readers having 2D image sensors read 1D symbols by capturing a 2D image representation of an area containing the 1 D symbol, preliminarily analyzing the image data represented in the area to determine that the image data comprises a representation of a 1D symbol, and then launching a scan line in an attempt to decode for the 1 D symbol determined to be present. In either case, a full frame 2D image representation is captured in order to decode for a 1 D symbol.
Capturing a 2D image representation requires a substantial amount of time, especially in applications wherein one or more “test” frames of image data must be captured prior to capture of a frame that is subjected to processing. Furthermore, assuming a constant processing speed, the time required for an optical reader to capture a 2D image representation increases with the resolution of the image sensor which is incorporated in the reader. Currently available CMOS mega pixel image sensors have low frame clock out rates of about 15 frames per second (FPS).
A user's satisfaction with an optical reader often varies directly with the decoding speed of the optical reader. Given that higher resolution, including mega pixel readers, are expected to grow in popularity, the frame capture time will become an increasingly important factor for consideration in performance of an optical reader.